钢管混凝土桁梁受弯试验研究

针对钢管混凝土桁式受弯构件的整体受力性能,设计并制作了钢管混凝土桁梁试件,进行了四分点对称加载,分析了钢管混凝土桁梁的变形与应变分布模式、破坏模式和承载力等。试验结果表明:钢管混凝土桁梁变形比实腹梁小很多且主要集中于边段;桁梁节点受力复杂,节点承载力是结构承载力的控制因素;弦杆填充混凝土可增大弦杆的径向刚度并约束节点变形,避免发生弦杆钢管塑性失效,从而提高节点承载力。四分点对称荷载作用下,全焊桁梁腹杆实际分担的轴力值小于铰接桁架的计算值,弦杆承受了较大的弯矩;节点破坏前桁梁试件边段腹杆有较明显的剪切变形。

Experimental Research on Concrete-Filled Steel Tube Truss Girder Under Bending

In order to make further investigation into the global action of concrete-filled steel tube(CFST) truss girder,experiment of CFST truss girder specimen under symmetrically quarter loading was carried out.Specimen of CFST truss girder was fabricated according to dimensions of stiffening girder and truss arch rib of several built bridges and code for design of steel tube structure.Based on the measured deflection and strain of specimen during experiment,the deformation,strain increasing mode of steel tube,failure mode and load-carrying capacity of joints as well as the whole girder were analyzed.The test result shows that deflection of CFST truss girder is mainly attributed to deformation of shear-bending parts and much smaller than that of solid web girder.The behaviors of joints are complex and its ultimate load capacity will control that of the truss girder.Filled concrete in the chord tubes can increase the member's radial rigidity and keep it from plastic failure thus strengthens the joints.Under the symmetrically quarter loading,axial forces in web members for CFST welding truss girder are commonly less than that of hinged truss,and the chord members are subjected to prominent bending moment.Before the failure of joints,obvious shear deformation among web members can be observed during shearing-bending parts.